New Developments and Basis of Presentation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Mar. 31, 2016 |
Jun. 30, 2016 |
Jun. 30, 2016 |
Jun. 10, 2016 |
|
| Basis Of Presentation [Line Items] | ||||
| Net proceeds from sale | $ 29.2 | |||
| Westlake Chemical Corporation and Lagoon Merger Sub, Inc. [Member] | ||||
| Basis Of Presentation [Line Items] | ||||
| Merger agreement date | Jun. 10, 2016 | |||
| Merger consideration per share | $ 33.00 | |||
| Termination fee | $ 77.7 | |||
| Merger-related expenses | $ 8.4 | $ 13.6 |